Lohr's Ph.D. study was part of a larger project on the Ijen Crater Lake on East Java, Indonesia. This crater lake is the largest collection of volcanic water in the world and is extremely acidic (pH 0.1). The acidic water slowly seeps away, and despite dilution by two tributaries in the area the pH of the river water remains very low. This water is used for agricultural and household purposes, which sometimes leads to the rice harvests failing. The very high aluminium content of the water - associated with the acidity - also plays an important role in this. Other elements such as fluorine, in the form of fluoride, form a direct threat for public health. The levels are not only alarmingly high in the river water but also in the groundwater and drinking water wells.
Within the large project scientists studied the geochemical and hydrological processes as well as the health risks. Ansje Lohr investigated the ecological effects of the acidic water. As well as having a harmful effect on the well-being of the local population, it adversely affects the biodiversity.
Lohr sampled the water at various locations. She observed that the neutral river water contained normal aquatic fauna, but that only mosquito larvae could survive the extremely acidic water. The diversity of microorganisms and algae was also very low. The inhibited breakdown of organic material was another ecological effect measured. Lohr established this using packs containing jati and bamboo leaves, which she suspended in the river at various locations. She determined the loss dry matter over a period of several m onths.
According to Lohr, one possible solution for the acidification problem is simply to prevent the crater water from mixing with both neutral rivers. She believes that this could be realised by channelling the flow of acidic water from the crater into the sea, which with its enormous water surface would not suffer any detrimental effects due to this small quantity of acidic water. Lohr wants to hold discussions with local authorities, other researchers and companies in order to arrange such a diversion or another solution. The biologist recently received a dissemination grant from NWO-WOTRO to support this.